Index: src/tclx/config/linux
--- src/tclx/config/linux.orig
+++ src/tclx/config/linux
@@ -5,6 +5,6 @@
 #------------------------------------------------------------------------------
 #
-SYS_DEP_FLAGS=-DTCL_HAVE_SETLINEBUF -DTCL_32_BIT_RANDOM -DTCL_POSIX_SIG -DTCL_TM_GMTOFF
+SYS_DEP_FLAGS=-DTCL_HAVE_SETLINEBUF -DTCL_32_BIT_RANDOM -DTCL_POSIX_SIG -DTCL_TM_GMTOFF -DTCL_IEEE_FP_MATH
 LIBS=-lm
 RANLIB_CMD=ranlib
 MCS_CMD=true
